This invention relates to the manufacture of seamless tubing and more particularly to a positive drive hose reel apparatus for a water cooling system mounted on a linearly movable thrust block for piercing and reeling mills.
In the manufacture of seamless tubing, one of the initial operations is a piercing of a heated cylindrical solid metal billet by a pair of angularly disposed driven mill rolls which force the billet over a piercing point on the end of a mandrel bar. The mandrel bar extends away from the mill rolls in the direction of longitudinal movement of the billet over the piercing point, for a distance that is at least as great as the length of the longest tube to be formed on the mill. The rear end of the mandrel bar is supported by a movable carriage or thrust block which is adapted to be retracted, after a pierced billet has passed through the mill rolls, to withdraw the bar from the tube so that the tube can be removed from the outlet table on which it is received after the piercing operation. The thrust block is thereafter advanced, to return the bar to a working position with the piercing point adjacent the mill rolls.
To avoid overheating of the mandrel bar and piercing point, the thrust block is provided with an arrangement for supplying cooling water to the piercing point during the tube forming operation. Typically, the cooling water is supplied to the movable thrust block by an elongated flexible hose interconnecting the thrust block with a water supply. During each operating cycle of the mill, the thrust block executes a substantial linear movement in order first to bring the piercing point to its working position and thereafter to withdraw the mandrel bar from the formed tube. The total distance traversed may be in the order of 24 meters or so. Therefore, it is necessary to provide means to pay out the flexible hose when the thrust block is advancing the piercing point to its working position, and to take up the excess length of hose during the retracting motion of the thrust block, all while the thrust block is moving at high speed.
The prior art has heretofore proposed several means for feeding and taking up the flexible hose. For example, the hose feed and take up function has been accomplished by a spring driven reel, carried by the thrust block. In accordance with this proposal, the flexible hose is wound on the reel. As the thrust block advances towards its working position, the reel unwinds against the action of the spring and the hose is advanced. When the thrust block retracts, the spring drive of the reel will cause it to rotate and thereby take up the excess length of hose. In another prior proposal, a festoon arrangement has been provided with the hose being suspended in intervals along a slide way positioned adjacent to the outlet table of the piercing mill. In accordance with this proposal, a suitable length of hose can slide back and forth along the slide way as the thrust block advances and retracts. Recent developments in the design of piercing and reeling mills have, however, substantially increased the speed of operation of the mills in order to derive improved efficiencies. Consequently, the thrust block will now be moved at high speeds during the stripping cycle, and neither of the above described prior hose feed arrangements is suitable for accommodating high speed thrust block movement on a practical basis.
As one of its basic objectives, the present invention provides a novel positive drive hose reel apparatus which will both pay out and recoil the flexible hose in accordance with the speed of movement of the thrust block. The positive drive arrangement disclosed herein is a simplified, yet highly effective arrangement wherein the linear movement of the thrust block will be directly translated into the positive drive for the flexible hose pay out and take up. Consequently, the arrangement of the present invention will accommodate the high operating speeds of the thrust block and insure a relatively foolproof hose feed.
In the illustrated form of the invention, a rotatable hose reel is carried by the thrust block. A suitable length of flexible hose is wound on the reel with one end thereof connected to the water cooling system of the thrust block and the other end connected to a remote water supply. A positive drive for the reel is provided by a cable, extending the full length of the path of movement of the thrust block, and connected under tension at both ends. The cable has one or more wraps around a separate cable-receiving section of the hose reel. Linear motion of the thrust block will pull on the cable causing it to rotate the hose reel in a rotational direction to either pay out the hose or take up excess hose length, depending on whether the thrust block is advancing or retracting. The rate of rotation of the reel will at all times be appropriately related to the speed of linear movement of the thrust block and the length of hose payed out or taken up will always be proper.
Pursuant to another feature of the present invention, a cable-receiving section of the hose reel is of a "stepped" configuration, to provide that the center axis of the hose will be on the same radius as the center of the cable. This will insure the proper rotational speed of the hose reel in accordance with the linear speed of the thrust block. The longitudinal dimension of the hose reel and cable-receiving section are of a sufficient length to accommodate the wound portions of the hose and cable respectively, when fully coiled, in a single layer thereby maintaining the advantage of the "stepped" configuration.